1. Field of the Invention
This invention relates generally to spectrographic measuring methods and systems.
2. Discussion of the Related Art
Spectrally analyzing a sample typically involves illuminating the sample with light and measuring the intensity of absorbed, scattered, or fluoresced light by the illuminated sample as a function of wavelength. The sensitivity of a spectral analysis may depend strongly on several lighting conditions.
One important lighting condition relates to the intensity of background light in the light detector used for the spectral analysis. Background light may include illumination light and light scattered, absorbed, or fluoresced outside of the sample.
Background light may wash out absorption, scattering, and/or fluorescence by the sample.
Another important lighting condition relates to the intensity of illumination light at the sample. Typically, the spectral response of a sample will be larger if the intensity of illumination light therein is larger. The intensity of illumination light in a sample is limited by physical constraints. For example, diffraction limits the ability to focus a light beam to a diameter smaller than the wavelength. Thus, diffraction will limit the ability to increase illumination intensities in a sample through focusing.
During spectral analysis, it is often desirable to produce lighting conditions that increase overall sensitivities.